Recent advances in biologic therapy have revolutionized the treatment of psoriasis. Risankizumab, a humanized monoclonal antibody targeting interleukin 23A, is the newest Food and Drug Administration (FDA)-approved biologic agent for the treatment of moderate-to-severe plaque psoriasis. Due to its potential immunomodulating effect, considerations for serious infections such as hepatitis B (HBV) and hepatitis C (HCV) are important when initiating biologic therapy; in particular, the serious complications of HBV and HCV reactivation. Given that controlled clinical trials investigating new biologic agents often exclude patients with HBV and HCV infections, safety data on their use in this cohort are limited with recommendations constantly changing. We report a case of a 53-year-old man with severe plaque psoriasis, resolved HBV infection, and treated chronic HCV infection. He has a complex medical history of chronic liver cirrhosis with resulting esophageal varices, portal hypertension and thrombocytopenia, melanoma, and testicular cancer. Psoriasis was successfully treated with risankizumab, reflected by a reduction in Psoriasis Area and Severity Index (PASI) score from 57.6 to 0.0 after 3 injections of 150 mg at week 0, week 4 and week 16. His medical comorbidities have remained stable with no evidence of hepatitis reactivation since treatment onset. Data on the use of IL-23 inhibitors in the setting of HBV and HCV infections are limited. Involvement of gastroenterology and serial monitoring of aminotransferases are crucial. Derangements in aminotransferases should prompt testing of HBV surface antigen or serum HBV deoxyribonucleic acid, and HCV ribonucleic acid.

Chronic plaque psoriasis is often associated with autoimmune bullous diseases. Dermatitis herpetiformis (DH) is a rare immunobullous disease that has been linked to celiac disease (CD). To our knowledge, the coexistence of psoriasis and DH is uncommon, and has only been described in anecdotal reports. We report a case of chronic plaque psoriasis complicated by DH in a 60-year-old patient with no known history of CD or associated symptoms. In our patient, DH presented atypically as multiple vesicles along the edges of psoriatic plaques located on the back and hips, and as vesiculobullous eruptions on the fingers. The patient was successfully treated with a combination of dapsone and a gluten-free diet for DH, and secukinumab for psoriasis. This case highlights the importance of screening for CD in patients with psoriasis, as well as other concomitant autoimmune diseases. A gluten-free diet should be trialled in psoriatic patients with positive CD serology.